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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>

</body>
<script>
    Array.prototype.myShift = function () {
        var newArray = arr.splice(0, 1).join('');
        return newArray
    }
    // 使用
    var arr = [11, 22, 33]
    arr.myShift()
    console.log(arr); 
</script>

</html>